I particularly like 'chess-scapes' and I have done a few of them myself. I find it intriguing and the pieces come to life when photogrpahed in certain compositions. I think this composition could be improved somewhat by shifting your angle of view to the left just slightly where the pieces in the foreground fall inbetween the pieces facing us in the back. This would possibly create some interesting separation within the image. I believe this photo may have scored below average in the challenge because of the particular perspective you chose. The perspective itself doesn't provide enough impact to sway the voter.
I see you have gone for a lack of depth by using a longer lens. Interesting. The average person might have tried to exaggerate the perspective for this challenge.